Semiconductor dice are packaged to enable the semiconductor to make electrical, thermal, and mechanical contact with the circuitry and/or circuit board in which it is mounted. However, the packaging itself adds or modifies the electrical, thermal, and mechanical properties of the die so that in the resulting packaged product the circuitry on the die performs differently than in the case of the die alone.
Product designers try to minimize the ‘parasitic’ effects of unwanted capacitance or inductance induced by the package. These parasitic effects tend to cause a reduction in performance of the product from the design specifications.
Special care must be taken in package design when devices, such as MOSFETS, are operated at high power levels and RF frequencies. Heat generated during the operation of the device must be dissipated, and unwanted capacitances and inductances must be minimized to attain maximum operating frequency, power gain, and proper matching from stage to stage. Current RF power device packages are limited in both power output and signal operating frequency capabilities in an effort to control unwanted capacitance and inductance.
For example, some RF power packages are limited to an operating frequency of approximately 30 megahertz (MHz) for high (>1 kilowatt) output power applications. In particular, conventional high power RF packages are generally limited to use with signal frequencies much lower than 1 MHz for an output power limit of a few hundred watts or are limited for use with signal frequencies less than 10 MHz for an output power limit of a few watts to approaching 1000 W. Other known high power RF power packages are generally limited for use with signal frequencies less than 30 MHz for an output power of a few hundred watts and approaching 1 kilowatt (kW). In addition, few of the known devices have an integrated driver. Most of the known classes of devices employ a direct-copper-bonded (DCB) alumina substrate. The DCB alumina substrates are cost effective but provide poor thermal performance, which makes their use in very high power applications a poor choice.
Unfortunately, developments in circuitry require increasingly higher signal frequencies at high output power levels. There is a need in the art for a high power RF package arranged for use with operating signal frequencies of hundreds of MHz.